Thin conductors on both sides of a thin insulator are connected by wires to a remote switch. Slide it between the batteries. It breaks the connection until the switch is turned on.
Step 1: Why?
In this case, the battery powered loud and obnoxious talking halloween skull was the face of Leaf Boy, a leaf stuffed guy. Too much trouble to get to the power switch, so he needed a power switch on a wire.
Also it would make him shut the heck up until someone was in the right spot for him to yell at them.